Vol. 9
January Issue
Year 2008

Off the Beaten Track

in Vol. 9 - January Issue - Year 2008
Juan's Amazing Autogiro

Fairey Rotodyne for 48 passengers

“Juan, Juan ¿dónde estás?” – No reply – “Juan, where are you?” The tone of his mother’s voice told  Juan that it would be better to remain hidden behind the bushes, out of view and out of harm’s way.  After all, these were his summer holidays and a boy his age had the right to relax after a gruelling school year. Yes, definitely, the more he thought about it, the more comfortable it felt to lie on his back on the warm grass as he watched the slow, lazy flight of the storks overhead. He gaped at the apparent ease with which the birds controlled their descent. He marvelled at the slight, almost imperceptible movement of the tail feathers and the full, majestic opening of the wings which brought the splendid creatures to land with millimetric precision on their nests high up on the chimneys. Would humans ever be able to duplicate these movements in flight with the same degree of accuracy?

Juan de la Cierva was born in Murcia, Spain, in 1895. He was only eight years old when the news of the Wright brothers’ flight spread throughout the world like wildfire, and like wildfire it inflamed the young boy’s imagination. Aviation arrived in Spain in 1910 and Juan’s father took him to watch the first demonstration flights in Barcelona and Madrid by the Frenchman Julien Mamet. Now Cierva knew where to focus his keen interest in mechanics. That same year, at the age of fifteen, he teamed up with two good friends and started building huge kites and gliders which could carry the weight of a person. By the age of seventeen, Cierva had built his first powered aircraft, which stalled and crashed during a test flight, almost killing the pilot. This incident encouraged Cierva to look for a means to sustain lift at low speeds, especially during take-offs and landings, crucial moments in which many airplanes built in those early years would stall and drop to the ground like rocks.

Cierva’s solution was to substitute the wings with self-rotating rotor blades mounted horizontally on the top of the aircraft. These blades were tilted back and were not powered by the engine, but rotated freely with the air pressure which was created as the aircraft was thrust forward by an engine-driven propeller. In this way, rotating wings provided the lift previously given by fixed wings. This system also proved invaluable in case of engine failure, another common occurrence in those years. In fact, the air rushing through the rotor during a vertical descent forced the blades to rotate even faster, providing maximum lift and allowing the aircraft to come to a soft landing.

Cierva called his invention an “autogiro” and named his first model “Cierva C-1”, which had its first successful test flight in January 1923. Other models followed in rapid succession, as Cierva continued to improve on the design and the reliability of his creation. One of the most serious problems he had to face was the rolling movement of the aircraft caused by the asymmetry of lift between the advancing and retreating blades of the rotor. He overcame this difficulty by attaching each blade to a flapping hinge which would automatically compensate the different movements of the blades. What evolved was an aircraft that could fly slower than an airplane, but faster than a helicopter.

In 1925, Cierva brought his C-6 model to England, where demonstration flights were so successful that the British government invited him to continue his work in the UK. Cierva soon teamed up with a Scottish businessman named James Wier and founded the Cierva Autogyro Company. In the following years, the Spaniard focused most of his efforts on the design and manufacture of the rotor systems, granting licenses for the manufacture of the airframes to companies such as Avro, Panall, DeHavilland and Westland. He also sold manufacturing rights to companies in Russia, Japan, France, Germany and the U.S.A.

By the 1930’s and 1940’s, autogiros, or gyroplanes as they became known in the U.S., had become widespread in several countries, transporting passengers, goods and providing surveillance service. Gyroplanes were also used for mail deliveries from the roofs of post offices. A forty-eight passenger model was developed in the 1950’s. Rotor technology created by Cierva was subsequently used to develop the helicopter. As opposed to the autogiro, the helicopter can hover, thanks to its engine-powered rotor, however Cierva had discarded the possibility of developing the helicopter as he considered the mechanics too complicated and dangerous.

By Giovanni Gregorat, Contributing Editor MFN
& Sales Manager, Pometon Abrasives

Author: Giovanni Gregorat